A favorite of Thomas Jefferson's in his expansive garden at Monticello, Paris White Cos leaf lettuce is popular among modern day gardeners too, including those who don't have quite as much space. Also referred to as romaine, "Cos" is a type of lettuce that grows in a cylindrical fashion, with several layers of tightly wrapped leaves forming an elongated lettuce head. The long, broad leaves also have "midribs," which are the pencil-wide stalks that run through their centers and create much of their irresistible crunch. Ideal for Caesar salads but fantastic any way you like lettuce, Paris White Cos is particularly great at resisting wilt and keeping its crispness on toasted sandwiches like paninis and BLTs.